Improvement in instrument for describing spirals



cannoni) GRANDELL, or WASHING-Ton, DISTRICT oil1 continent.V

Letters Patent No. 99,853, dated February 15, 1870.

IMPRQVEMENT IN INSTRUMENT `IZR DESCRIBING- SPIRALS, &c.

The Schedule referred to in these Letters Patent and making part of the same To all whom it may concern:

Beit known that I, GERMOND CRNDELL, ot' Washington, in theconnty of Washington, and District of Columbia, have invented a Machine for Drawing or `Describing a Scroll; and I-do llereby declare that the lollowing is a full and exact description thereof, reference being had to the accompanying drawings and to the letters of reference marked thereon.

Tile nature of my invelltion consists in so combining a screw with a spur-wheel and a point or foot, that when the foot or point, which corresponds to one foot of a pair of dividers, is placed in position upon aplain, and the spur-wheel resting llpon the salue plain, the forward motion, as in describing acircle with dividers,

turns the wheel which'acts as one foot, and that turns the screw, wllicll, passing through a. nut above the point, constantly increases the distance between the two points, thereby describing a scroll instead of a circle.

To enable others skilled in the `art to make and use my invention, I will Iproceed to describe its construction andoperaticn by referring to the drawing, in whicho represents the point corresponding to one foot oi' a pair oi' dividers, when used in describing a circle.

b is a screw passing through the nut d, which is secured to the body of the instrument e, or may be made as a part of it. v

c isa spurwheel fastened to theA end of the screw bl, and corresponding to the other .foot of apair of dividers. This wheel is made so as to be taken olf at pleasure, and replaced with dierent sizes, according to the plan of the scroll to be described, as sllown in Figures l, 2, and 4,- like letters representing like palts in each figure. -Y

y g is the other end ofthe piece of which a, is the first, on which is a screw which passes through the nut f, as shown at Figure 3. Tile nut f is attached to the body of the instrument, so that on turning it either way, it moves the point a up or down. The piece of which (l and g are the two extremes is separated longitudinally a part of the way, so as to permit the body of the screw b to pass freely throughit, as sho'wn at tig. 3. By turning the nutf in the rightdirectior, this piece may be brought up against the screw b and conne it, so that a circle may be described instead of a scroll, it' desired. VThe body of theinsttument may be made of metal or wood, and of any desired form. 'lhe screw, also, may be made with one or more threads and of 4dierent lengths, as required. The

wheels, also, may be made of two pieces instead'of one.

concave on the vinside so as to leave a space there for ink in `case ot' drawing on paper. ',lhese two adjustable wheels lnay be cut in points like the spur-wheel, solid, or they may be made without teeth, il'a smooth continuous lille is desired. to the screw by means of a set-screw, so that by loosening the set-screw, and coniining the screw b by means of the nut f, the wheel c will turn on the screw b, and thus describe a dotted circle, it desired. f

Tile large end of the body oi'v the instrument e be-` ing a plain, perpendicular to the screw b, as shown iu iig. 4, by placingr this end against the edge ota board or other substance, and setting the spur or pointed tooth-wheel c at the desirable starting poillt, adeparting dotted line may be drawn to said edge by the points of the wheel c penetrating the suritcc, it' the solid wheel be used, or a dotted lille it' the hollow wheel with ink be used on papel', whose angle. will be greater or lesser, according to the size ot' the wheel ein# ployed. By setting the wheel c at any desirable 'distance from the said edge, with one of its point-s down,

and then confining the screw b by lneansot" the clamp-- ing arrangement, shown in the sallle ligure, parallel scribe lines may be drawn to the said edge, as with an ordinary gauge; Iand by loosening the set-screw h, dotted parallel lines instead of scribe lines may be drawn.

passes, and provided -witll the adjustable point ato a yoke or stirrnp, which, by means of the screw nut f, lnay be made tecla-mp the through screw b when desired, the whole f'orl'ning adrawing instrument capable .of describinga spiral lille or a circle, and also as a gauge, a parallel, or taper straight line, substantially in themanner shown and described.

GERMOND GRANDELL.

Witnesses:

EDM. F. BROWN, AUGUST BAsrnnT.

They may also beattached 

